Fig. 3. Relative activity of carbonic anhydrase in different pooled segments of the midgut of larval Aedes aegypti. Midguts were dissected from early fourth-instar larvae and separated into gastric caeca (GC), anterior midgut (AM), posterior midgut (PM) and Malpighian tubules (MT). The relative activity of carbonic anhydrase was measured using the O18 mass spectrometry method (Silverman and Tu, 1986) normalized to total protein content. The activity of the anterior midgut was lower than that of the water blank and, thus, is set as ‘zero’ activity. Values are means + S.E.M., N=3.
